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Ionic equations
This chapter is just showing how to work ionic equations, thats fine. But it says in this reaction only some of the ions are involved...
AgNO3(aq)+NaCl(aq) = AgCl(s)+NaNO3(aq)
so the silver nitrate ad the sodium chloride is happily dissolved in water, they are broken up into seperate ions by the polar water particles. Now it says the silver ions will always react with the chloride ions to make a precipitate of silver chloride, and that the sodium and nitrate are not involved in any reaction, well clearly they are because they have formed sodium nitrate... it clearly states 'the nitrate and sodium ions are present in the mixture but do not change, they are spectator ions'.
1.Can someone clear that up?
2.When these ions are dissolved in the water, why do they make silver chloride and sodium nitrate, why dont they go back to their original states, basicaly what governs which ions react with which. I thought valency but what if valency is the same.
Pitch it at AS level please, cheers
AgNO3(aq)+NaCl(aq) = AgCl(s)+NaNO3(aq)
so the silver nitrate ad the sodium chloride is happily dissolved in water, they are broken up into seperate ions by the polar water particles. Now it says the silver ions will always react with the chloride ions to make a precipitate of silver chloride, and that the sodium and nitrate are not involved in any reaction, well clearly they are because they have formed sodium nitrate... it clearly states 'the nitrate and sodium ions are present in the mixture but do not change, they are spectator ions'.
1.Can someone clear that up?
2.When these ions are dissolved in the water, why do they make silver chloride and sodium nitrate, why dont they go back to their original states, basicaly what governs which ions react with which. I thought valency but what if valency is the same.
Pitch it at AS level please, cheers
Scroll to see replies
Ag+(aq) + NO3-(aq) + Na+(aq) + Cl-(aq) --> Ag+Cl-(s) + Na+(aq) + NO3-(aq)
At the start, all the different ions are free in solution as Silver Nitrate and Sodium Chloride are both soluble. Silver Chloride forms which has a low solubility, so becomes a precipitate (solid). Sodium Nitrate is a soluble salt and so remains in solution. The equation above is what is really happening. As you can see, the Na+ and NO3- remain unchanged, and are not involved in the reaction; hence, they are spectator ions. This is known as a double precipitation reaction - they are very common.
As for number 2, we never really had to learn it. I'm not sure you would require that much detail, just know what I have mentioned above. Best of luck.
At the start, all the different ions are free in solution as Silver Nitrate and Sodium Chloride are both soluble. Silver Chloride forms which has a low solubility, so becomes a precipitate (solid). Sodium Nitrate is a soluble salt and so remains in solution. The equation above is what is really happening. As you can see, the Na+ and NO3- remain unchanged, and are not involved in the reaction; hence, they are spectator ions. This is known as a double precipitation reaction - they are very common.
As for number 2, we never really had to learn it. I'm not sure you would require that much detail, just know what I have mentioned above. Best of luck.
The textbook clearly shows the sodium and nitrate to show formed sodium nitrate. It would make sense if it was as you have written it, but its definitely NaNO3 which surely means a reaction has taken place... grrrrr
Here is a table of solubility rules. All common nitrates are soluble, and Silver Chloride is one of the chlorides that is insoluble.
Ok, so the silver chloride is insoluable and so remains chemicaly bonded, and the sodium and nitrate remain soluable, so they remain free ions. I take it the textbook has written it as this for the sake of a correct equation, even though the NaNO3 will seperate anyway?
On another note, which font is it which is used to correctly write equations and the symbols which come with them, subscript or something....
On another note, which font is it which is used to correctly write equations and the symbols which come with them, subscript or something....
Ionic equations are a nightmare. I did chemistry A level for almost 2 school years and still don't really get them.
A spectator ion is the ion that occurs on both sides of the ionic equation and can therefore be disregarded.
First split only the aqueous reactants and products into their ions NEVER the solids.
(Ag +) + (NO3-) + (Na+) + (Cl-) --> AgCl + (Na+) + (NO3-)
The spectator ions in this equation are (NO3-) and (Na+) because they occur on both sides of the equation.
So the ionic equation after cancelling the spectator ions is
(Ag+) + (Cl-) --> AgCl
These equations are hard to make sense of at first but you'll get use to them in the end.
I hope this makes sense to you.
First split only the aqueous reactants and products into their ions NEVER the solids.
(Ag +) + (NO3-) + (Na+) + (Cl-) --> AgCl + (Na+) + (NO3-)
The spectator ions in this equation are (NO3-) and (Na+) because they occur on both sides of the equation.
So the ionic equation after cancelling the spectator ions is
(Ag+) + (Cl-) --> AgCl
These equations are hard to make sense of at first but you'll get use to them in the end.
I hope this makes sense to you.
LearningMath
Ok, so the silver chloride is insoluable and so remains chemicaly bonded, and the sodium and nitrate remain soluable, so they remain free ions. I take it the textbook has written it as this for the sake of a correct equation, even though the NaNO3 will seperate anyway?
On another note, which font is it which is used to correctly write equations and the symbols which come with them, subscript or something....
On another note, which font is it which is used to correctly write equations and the symbols which come with them, subscript or something....
Yes, you are correct. The equation in the book will have NaNO3(aq). The aqueous signifying that the ions remain in solution.
To do the + and - (at top of writing) and numbers at the bottom, you need what is called superscript and subscript. They are separate things you need to add to your toolbar in word. You need to right click on the toolbar running across the top of your word screen with the different tools on it. Then click on customise at the bottom. Click tools and then scroll until you find them. Drag and drop them onto your toolbar. You will soon learn how to use them. For example, click the 'Superscript' button and then type in +, then click it again to proceed typing normally.
Hope this helps.
callum Honisett
A spectator ion is the ion that occurs on both sides of the ionic equation and can therefore be disregarded.
First split only the aqueous reactants and products into their ions NEVER the solids.
(Ag +) + (NO3-) + (Na+) + (Cl-) --> AgCl + (Na+) + (NO3-)
The spectator ions in this equation are (NO3-) and (Na+) because they occur on both sides of the equation.
So the ionic equation after cancelling the spectator ions is
(Ag+) + (Cl-) --> AgCl
These equations are hard to make sense of at first but you'll get use to them in the end.
I hope this makes sense to you.
First split only the aqueous reactants and products into their ions NEVER the solids.
(Ag +) + (NO3-) + (Na+) + (Cl-) --> AgCl + (Na+) + (NO3-)
The spectator ions in this equation are (NO3-) and (Na+) because they occur on both sides of the equation.
So the ionic equation after cancelling the spectator ions is
(Ag+) + (Cl-) --> AgCl
These equations are hard to make sense of at first but you'll get use to them in the end.
I hope this makes sense to you.
Exactly. Don't ask me why I never explained what the ionic equation was.
I'm finding is whole area a complete pain, neither the textbook or anyone here seems to be able to provide a set of rules which i need to identify the ionic reaction and the spectator ions.
Heres another reaction from which i am supposed to be able to tell the ionic reactants, products and spectator ions
NaOH(aq) + HCl(aq) = NaCl(aq) + H2O(l)
I mean wtf? Why do the Hydrogren ions and hydroxide ions react, and the Na and Cl do not! Bascialy i'm being told a list of things which happen, without being given a reason, which is completly useless when asking me to work out more equations
What makes ions either reactants or spectators, i need rules/explanations!
Heres another reaction from which i am supposed to be able to tell the ionic reactants, products and spectator ions
NaOH(aq) + HCl(aq) = NaCl(aq) + H2O(l)
I mean wtf? Why do the Hydrogren ions and hydroxide ions react, and the Na and Cl do not! Bascialy i'm being told a list of things which happen, without being given a reason, which is completly useless when asking me to work out more equations
What makes ions either reactants or spectators, i need rules/explanations!
Cheers, im just searching for subscript tool now.
The ionic equation itself isnt hard. Just writting the charges on the ions, fine no prob.
But i see nothing which would stop me writting (2Na+) + (O2-) = 2NaO
The ionic equation itself isnt hard. Just writting the charges on the ions, fine no prob.
But i see nothing which would stop me writting (2Na+) + (O2-) = 2NaO
LearningMath
I mean wtf? Why do the Hydrogren ions and hydroxide ions react, and the Na and Cl do not! Bascialy i'm being told a list of things which happen, without being given a reason, which is completly useless when asking me to work out more equations
What makes ions either reactants or spectators, i need rules/explanations!
What makes ions either reactants or spectators, i need rules/explanations!
In a neutralisation reaction your OH- and H+ react to form a chemical bond (i.e. to get H2O), whilst sodium and chloride ions remain aquated in solution.
You can just split up the ions and see which are the same on both sides of the equation (these are spectator ions) and which undergo a chemical change.
So
NaOH(aq) + HCl(aq) ---> H2O(l) + NaCl(aq)
can be split up into
Na+(aq) + OH-(aq) + H+(aq) + Cl-(aq) -------> H2O(l) + Na+(aq) + Cl-(aq)
Clearly, you can't separate water into ions (the autoprotolysis constant KW is very small), so you have sodium and chloride ions on both sides, but OH- and H+ react to form water.
But it's admittedly a bit difficult to 'just know' what happens if you're not familiar with the reacting species. If state of matter symbols are included, a big tip is that species with '(aq)' are typically solvated ions and can often be split into the individual ions; you can't (normally) do anything about any other state of matter however.
The reaction here is H+ + OH- ----> H2O, the enthalpy of neutralisation remains the (pretty much) same regardless of the counter ions so NaOH + HCl -> NaCl + H2O is the same as KOH + HCl -> KCl + H2O. So they do not partake in the reaction - spectator ions.
LearningMath
But i see nothing which would stop me writting (2Na+) + (O2-) = 2NaO
Well, first of all, that equation as written makes no sense. You're doing either
2 Na+ + O2- ---> Na2O (to get the oxide)
or
Na+ + 1/2 O22- ---> NaO (to get the peroxide)
or
Na+ + O2- ---> NaO2 (to get the superoxide)
But why would anything be stopping you from writing this?
Sinuhe
In a neutralisation reaction your OH- and H+ react to form a chemical bond (i.e. to get H2O), whilst sodium and chloride ions remain aquated in solution.
You can just split up the ions and see which are the same on both sides of the equation (these are spectator ions) and which undergo a chemical change.
So
NaOH(aq) + HCl(aq) ---> H2O(l) + NaCl(aq)
can be split up into
Na+(aq) + OH-(aq) + H+(aq) + Cl-(aq) -------> H2O(l) + Na+(aq) + Cl-(aq)
Clearly, you can't separate water into ions (the autoprotolysis constant KW is very small), so you have sodium and chloride ions on both sides, but OH- and H+ react to form water.
But it's admittedly a bit difficult to 'just know' what happens if you're not familiar with the reacting species. If state of matter symbols are included, a big tip is that species with '(aq)' are typically solvated ions and can often be split into the individual ions; you can't (normally) do anything about any other state of matter however.
You can just split up the ions and see which are the same on both sides of the equation (these are spectator ions) and which undergo a chemical change.
So
NaOH(aq) + HCl(aq) ---> H2O(l) + NaCl(aq)
can be split up into
Na+(aq) + OH-(aq) + H+(aq) + Cl-(aq) -------> H2O(l) + Na+(aq) + Cl-(aq)
Clearly, you can't separate water into ions (the autoprotolysis constant KW is very small), so you have sodium and chloride ions on both sides, but OH- and H+ react to form water.
But it's admittedly a bit difficult to 'just know' what happens if you're not familiar with the reacting species. If state of matter symbols are included, a big tip is that species with '(aq)' are typically solvated ions and can often be split into the individual ions; you can't (normally) do anything about any other state of matter however.
Why do the Na and Cl not react to form NaCl, they have opposite charges, so what is stopping them reacting?It is only the ions that occur on both sides of the equation when the you have split the aqueous reactants and products down that are the spectator ions. The ions that only occur on the left hand side of the equation are the raectant ions. Take your example above
NaOH(aq) + HCl(aq) = NaCl(aq) + H2O (l)
(Na+) + (OH-) + (H+) + (Cl-)= (Na+) + (Cl-) + H2O (L) (LIQUIDS DON'T GET SPLIT INTO IONS EITHER)
The spectator ions are (Na+) and (Cl-) because they are on both sides of the equation.
Now cancel these spectator ions to give the ionic equation.
You should get: (OH-)(aq) + (H+)(aq) = H20(l)
All ions are aqueous.
NaOH(aq) + HCl(aq) = NaCl(aq) + H2O (l)
(Na+) + (OH-) + (H+) + (Cl-)= (Na+) + (Cl-) + H2O (L) (LIQUIDS DON'T GET SPLIT INTO IONS EITHER)
The spectator ions are (Na+) and (Cl-) because they are on both sides of the equation.
Now cancel these spectator ions to give the ionic equation.
You should get: (OH-)(aq) + (H+)(aq) = H20(l)
All ions are aqueous.
Sinuhe
Well, first of all, that equation as written makes no sense. You're doing either
2 Na+ + O2- ---> Na2O (to get the oxide)or
Na+ + 1/2 O22- ---> NaO (to get the peroxide)
or
Na+ + O2- ---> NaO2 (to get the superoxide)
But why would anything be stopping you from writing this?
2 Na+ + O2- ---> Na2O (to get the oxide)or
Na+ + 1/2 O22- ---> NaO (to get the peroxide)
or
Na+ + O2- ---> NaO2 (to get the superoxide)
But why would anything be stopping you from writing this?
Yeah the oxide, my bad
That looks like a perfectly logical reaction to me, yet im being told that the H^+ + HO^- are the only ionic reactants here, well why can it not be the Na and Cl, what makes one the spectator. My textbook just has H2O as the correct answer.... !LearningMath
I'm finding is whole area a complete pain, neither the textbook or anyone here seems to be able to provide a set of rules which i need to identify the ionic reaction and the spectator ions.
Heres another reaction from which i am supposed to be able to tell the ionic reactants, products and spectator ions
NaOH(aq) + HCl(aq) = NaCl(aq) + H2O(l)
I mean wtf? Why do the Hydrogren ions and hydroxide ions react, and the Na and Cl do not! Bascialy i'm being told a list of things which happen, without being given a reason, which is completly useless when asking me to work out more equations
What makes ions either reactants or spectators, i need rules/explanations!
Heres another reaction from which i am supposed to be able to tell the ionic reactants, products and spectator ions
NaOH(aq) + HCl(aq) = NaCl(aq) + H2O(l)
I mean wtf? Why do the Hydrogren ions and hydroxide ions react, and the Na and Cl do not! Bascialy i'm being told a list of things which happen, without being given a reason, which is completly useless when asking me to work out more equations
What makes ions either reactants or spectators, i need rules/explanations!
It's concerned with how energetically favourable it is to "react" [if by that you mean to form new chemical bonds]. And that's something you can't just know - you have to do experiments to find those values out. But on top of that the reactions have to be kinetically favourable as well. Basically there are quite a few things which dictate whether or not a chemical reaction will take place, and while it is possible to predict it from data, you can't just "know" or "work out" chemical reactions without experiments.
LearningMath Why do the Na and Cl not react to form NaCl, they have opposite charges, so what is stopping them reacting?
Why do the Na and Cl not react to form NaCl, they have opposite charges, so what is stopping them reacting?What's stopping them from reacting is that sodium chloride is very soluble in water and doesn't exist as {NaCl}, but rather as Na+(aq) and Cl-(aq).
In other words, it is energetically (both enthalpically and entropically) more favourable for these charges to be solvated (i.e. lots of ion-dipole 'bonds' with water are formed) than for them to precipitate out of the solution to form an ionic solid.
The reasons behind this are complicated; solubility is sometimes explained using polarisability (Fajans' rules) and hard/soft character of ions, but I don't think you need to know any of this at A-level. I think you only need to know of a few among the ionic compounds (naturally!) that are sparingly soluble salts (such as AgBr). It's far easier to just learn these than to understand the theory behind it (although that is certainly also possible if you're keen).
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